1. Field of the Invention
The invention relates generally to nozzle devices and more particularly to a device for registering accurately with, and directing heated air about, modular electronic components, and to attaching or removing same from a substrate such as a printed circuit board.
2. Background of the Invention
Devices suitable for use in removing or installing modular electronic components from a substrate such as a printed circuit board include those which direct heated air at the terminals of the component from a source of heated air above the component to simultaneously melt the solder on each of the terminals. Examples of such devices are disclosed in U.S. Pat. Nos. 4,295,596 and 4,366,925. The devices in each of those two patents operate by directing hot air onto the terminals of a component, followed by removal of the component either mechanically or by the application of suction.
A disadvantage associated with the prior devices is that heated air is not delivered uniformly to the terminals, and this results in the generation of hot spots in the region of the terminals and non-uniform melting of the solder. In light of this, removal of the components is often hindered due to the fact that the solder at one or more of the terminals is not melted when the solder at the remaining terminals is melted, and removal of the component under these circumstances is often accompanied by damage to the component, to the leads and/or to the printed circuit board.
Other prior art hot air delivering systems employ double wall structures to direct the flow of heated air to the component terminals, the air being directed between the walls (which constitutes one of the walls of the double wall structure) of a nozzle and the walls (which constitutes the other wall of the double wall structure) of a vacuum pick-up device which engages the sides of the component. However, the vacuum pick-up device is also heated by the hot air and thus transfers an undesirable amount of heat to the component due to the large contact area of the pick-up device with the component.
It is therefore an object of the present invention to provide an improved device for delivering heated fluid to the sides of the component to uniformly melt solder at terminals disposed at the periphery of the component to facilitate clean installation or removal of the component from a substrate.
It is another object of this invention to provide an improved device of the foregoing type wherein heat transferred to a component is minimized due to the configuration of the heated fluid delivery structure.
It is another object of the present invention to provide an improved device of the above type incorporating a nozzle member having a lower depending skirt portion for obtaining an even distribution of heated air about the terminals in order to avoid the generation of hot spots and to ensure simultaneous melting of solder at all of the terminals to enable easy removal of the component from or installation of the component upon a printed circuit board.
It is a further object of the present invention to provide a constricted passageway to the heated fluid in the vicinity of the terminals to facilitate rapid and effective heat transfer from the heater fluid to the solder to be melted at the terminals.
It is another object of the present invention to provide an improved nozzle suitable for use in conjunction with a device which is used in the installing and removal of electronic components from circuits printed on a substrate.
It is another object of the present invention to provide a device of the subject type which employs a nozzle having a relatively precise component registration means, for locating the nozzle relative to the sides of the component as well as for locating the nozzle relative to the substrate, for precisely directing the flow of hot air from a source of hot air about the component to the solder which is associated with each component terminal or printed conductor on the substrate.
It is a further object of the present invention to provide a nozzle having inwardly-projecting walls having notched regions and a lower depending skirt, registration of top edges of the component with the notched regions in the projecting walls permitting accurate disposition of the skirt uniformly about the component and also permitting accurate positioning of the lowermost edge of the skirt above the substrate.
It is a further object of the present invention to provide, in a device of the above-described type, a generally rectangular nozzle which has a plurality of channel-shaped members, the channel-shaped members having generally parallel sidewalls which are disposed to project inwardly toward a central opening defined by the surrounding nozzle wall, lowermost edges of the inwardly-projecting sidewalls of the channel-shaped members having respective notches formed therein at a lowermost portion thereof, the notches being adapted to positively register with and snugly engage the top portion and sidewalls of a component.
It is a further object of the present invention wherein the inwardly projecting walls or channel-shaped members are thin and made of a material having low thermal conductivity whereby the amount of heat transferred to the component from the inwardly projecting walls or channel-shaped members is minimized.
It is a further object of the present invention to utilize the above-mentioned notches of the channel shaped members or the inwardly projecting walls to affect alignment of a component to be desoldered with the nozzle in that the component may have its position adjusted until the component engages all of the notches at which time alignment of the component with the nozzle is effected.
It is a further object of the invention to utilize the alignment effected above whereby after the component is desoldered, a new replacement component may be positioned in the notches and will be perfectly aligned with pads or the like on the board for connection thereto since the nozzle may be returned to exactly the same position it was in at the time the defective component was removed.
These and other objects of the present invention will be understood by those acquainted with the design and construction of such devices upon reading of the following detailed description in conjunction with the accompanying drawings.